The book Ningzi 甯子 "Master Ning" was a Confucian treatise compiled by the Warring States period 戰國 (5th cent.-221 BCE) scholar Ning Yue 寧越 who came from Zhongmou 中牟, Henan, and was teacher of King Weilie 周威烈王 (r. 425-402 BCE) of the Zhou dynasty 周 (11th. cent.-221 BC). The imperial bibliography Yiwenzhi 藝文志 in the official dynastic history Hanshu 漢書 says that the book Ning Yue was only one chapter long. The Qing period 清 (1644-1911) scholar Ma Guohan 馬國翰 collected information about Ning Yue and quotations from his teachings in the Lüshi chunqiu 呂氏春秋 and Shuoyuan 說苑. It can be known that Ning Yue was during his lifetime as famous as Confucius or the Mohist philosopher Mozi 墨翟, but, like these, never occupied a high office. Ning Yuan lived as a peasant but his friend said to him that thirty years of studies would liberate him from the bitterness of life. Ning thereupon, as a very ambitious person, fulfilled these studies within fifteen years.
Ning Yue is also wrongly mentioned in the book Huainanzi 淮南子, where the character 戚 for Ning Qi 寧戚 is erroneously written 戊, or 越, respectively. Ma Guohan's research results are to be found in his collectaneum Yuhan shanfang jiyi shu 玉函山房輯佚書.
Source: Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 1605. Changchun: Jilin daxue chubanshe.